1. Field of the Invention
The present invention relates to welding systems, and more particularly to a fusion welding system including a heating unit and welding device for combination heating and welding.
2. Discussion of Prior Art
The process of material joining and treatment is a necessary condition for the industrial progress. As such, fusion-welding systems have been developed for joining multi-component workpieces. One such system, laser spot and seam welding utilizes laser heat energy during joining, and is commonly used, for example, in the automotive industry.
These conventional systems are typically used to provide faster welding speeds and produce more accurate and precise welds than do counterpart resistance welding technologies. The power associated with the laser, and the material composition and initial state of the workpieces are directly proportional to the aspect ratio of weld depth to width. In other words, the more powerful the laser and focused the beam, the greater the heat energy density. However, while these benefits help minimize stresses experienced by the workpieces, they present other concerns. For example, these systems are typically limited by strict requirements of tolerance, porosity formation, poor gap bridgeability and hot cracking in the weld. Of further concern are the relative high costs associated with high-powered lasers (i.e., lasers having a power output greater than 4 kW), which are not solely a result of increased input energy demands.
These systems may also present construction concerns, where a high-powered laser is utilized to produce the fusion weld. The rapid change in temperature from initial room temperatures to temperatures greater than the melting range of the material, coupled with the speed of weld formation contribute to the production of pores formed by trapped gas, and cracking within the relatively narrow weld. The formation of pores and cracking further reduces the structural integrity of the weld.
Other welding systems, such as conventional hybrid laser-arc systems that feature the simultaneous application of heat generated from laser radiation and an electric arc, have also been developed. As with conventional laser welding, these hybrid systems often require high powered laser output for, and therefore, experience the same concerns during combination welding.
Thus, there is need in the art for an improved laser welding system that minimizes costs and the likelihood of construction inefficiencies that arise from high powered laser welding.